Phylogeney of Podocopid ostracods

Abstract

Ostracods are small aquatic crustaceans with a calcified, dorsally hinged bivalve-like carapace that can enclose the entire body. They are distributed almost every aquatic environment, such as shallow to deep pelagic environments, freshwater, brackish-water, and also subsurface-water. With an abundant and nearly continuous fossil record since the Ordovician, over 33,000 species of recent and extinct ostracods are currently known. Thus, ostracods are suitable materials for evolutionary biology. However, genomic information of this taxon is far from abundant. Starting in the Middle Jurassic, cypridoideans appear to have repeatedly invaded continental habitats and rapidly radiated. This explosive diver­sification leading to the “sudden appearance” of extant cypridoidean linages in the fossil record has hampered reconstruction of relationships in this group. To clarify the relationships among cypridoidean ostracods, I conducted the molecular phylogenetic analyses. In the results, relationships of superfamilies in Podocopida were almost consistent with previous classification systems. However, there was a problem with the internal systematics of the Cyprididae. Considering their ecology and morphology, I proposed to divide the family Candonidae into three different families. After receiving my doctoral degree while continuing research on ostracods, I am also conducting several researches in population genetics. Here I give an overview of these studies as well.